نتایج جستجو برای: مودم ofdm

تعداد نتایج: 10350  

2007
Heidi Steendam Marc Moeneclaey

In this paper, we consider different types of guard intervals for OFDM systems, i.e. cyclic prefix (CP), zero padding (ZP) and known symbol padding (KSP). We compare the different OFDM systems with respect to their SNR performance. We show that CP-OFDM and ZP-OFDM have exactly the same performance, whereas KSP-OFDM has a slightly worse performance. Further, we consider data aided channel estima...

Journal: :Intelligent Automation and Soft Computing 2023

Fifth generation (5G) wireless networks must meet the needs of emerging technologies like Internet Things (IoT), Vehicle-to-everything (V2X), Video on Demand (VoD) services, Device to communication (D2D) and many other bandwidth-hungry multimedia applications that connect a huge number devices. 5G demand better bandwidth efficiency, high data rates, low latency, reduced spectral leakage. To the...

2009
Zhiqiang Wu Zhijin Wu David A. Wiegandt Carl R. Nassar

Abstract OFDM (Orthogonal Frequency Division Multiplexing) is an excellent technology that will almost certainly play a large role in next generation wireless communication systems. However, in OFDM, no frequency diversity is exploited to improve BER performance. Today’s OFDM systems attempt to overcome this limitation by application of channel coding and interleaving, which requires a reductio...

Journal: :IEICE Transactions 2009
Haris Gacanin Fumiyuki Adachi

The use of frequency-domain interleaving on a frame-byframe basis for orthogonal frequency division multiplexing (OFDM) combined with time division multiplexing (OFDM/TDM) is presented. In conventional OFDM, FDE is not designed to exploit the channel frequencyselectivity and consequently, the frequency diversity gain cannot be obtained. To further improve the bit error rate (BER) performance of...

Journal: :CoRR 2017
Hirofumi Tsuda Ken Umeno

Orthogonal Frequency Division Multiplexing (OFDM) systems have been widely used as a communication system. In OFDM systems, there are two main problems. One of them is that OFDM signals have high Peak-to-Average Power Ratio (PAPR). The other problem is that OFDM signals have large side-lobes. In particular, to reduce side-lobes, UniversalFiltered OFDM (UF-OFDM) systems have been proposed. In th...

2012
K. Dhuness B. T. Maharaj

A method called offset modulation (OM-OFDM) is proposed to control the peak-to-average power ratio (PAPR) of an OFDM signal. The authors demonstrate the significant modulation, structural and performance differences between an OM-OFDM and CE-OFDM method. The OM-OFDM method in addition is able to accurately control the PAPR of a transmission for a targeted BER, which is currently not possible wi...

2013
Archana Ogale Shubhangi Chaudhary Anil J Patil

Multiple Transmit and receive antenna are now popularly used to form multiple input, multiple output (MIMO) channels to increase the capacity as well as to reduce the Bit Error Rate (BER). This paper describes the performance of Hybrid MIMO-OFDM (Orthogonal Frequency Division Multiplexing) models, which are developed & analyzed in Matlab ® Simulink. In this study 2×2 STBC-OFDM and 2×2 SM-OFDM s...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه بیرجند - دانشکده برق و کامپیوتر 1391

با پدیدار شدن تکنولوژی های جدید مخابراتی و با افزایش تعداد سیستم های بی سیم، طیف رادیویی هر روز کمیاب می شود. مطالعات نشان می دهد که رنج وسیعی از طیف به صورت بهینه استفاده نمی شود. از این رو، در سال های اخیر شبکه های رادیو شناختگر با هدف استفاده ی بهینه ازطیف فرکانسی در زمان و مکان به طور گسترده ای مورد توجه قرار گرفته اند. در این شبکه ها طراحی تکنیک های لایه فیزیکی، به دلیل این که کاربر ثانوی...

2013
Prakash Shanmuga priyan

In this paper, the high spectral efficiency of a transmission scheme called Time frequency training (TFT) Orthogonal frequency division multiplexing (OFDM) using MIMO system is proposed. The time frequency joint channel estimation for TFT-OFDM utilizes the time-domain training sequence without interference cancellation to merely acquire the time delay profile of the channel, while the path coef...

2010
V. K. Dwivedi S. Tripathi V. S. Tripathi R. Tripathi S. Tiwari

High peak-to-average power ratio (PAPR) of the transmit signal is a major drawback of multicarrier (MC) transmission such as orthogonal frequency division multiplexing (OFDM) system. This paper presents a novel Reed-Solomon (RS) codes based MC transmission scheme for reduction of PAPR called RS Turbo coded OFDM system. The reduction of PAPR of OFDM signal is obtained through a proper selection ...

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